1. Field of the Invention
The present invention is in the field of tools used to retrieve lodged or stuck items, called fish, from a well bore or casing.
2. Background Art
In the art of well drilling and workover, it is common to have a need to retrieve a stuck tool or other item from the well bore or casing. For the purposes of describing the invention herein, the terms casing and bore hole should be understood to mean any well bore, casing, or other tubing within which items may be lodged or stuck. Stuck items are commonly called fish. The fish may be a broken tool which has inadvertently stuck in the casing, or it may be a tool such as a whipstock, which is intentionally installed in the casing, to be removed or fished out later. Some types of fish have specially designed fishing tools which are suitable for latching onto a fishing contour on the uphole end of the fish. Others may be retrievable with a more general purpose fishing tool which is designed to latch onto many different configurations of fish. One example is a latch mechanism made up of a collet and a central spear, in which the central spear assists the collet in latching onto the fish.
Regardless of whether the fish is to be retrieved with a specially designed fishing tool or with a general purpose fishing tool, it is necessary for the tool to align with the fish, to a greater or lesser degree, depending upon the particular fish and the particular fishing tool. In some cases, as the fishing tool is run into the hole, the latch mechanism may be generally aligned with the center of the casing or bore hole, and the upper end of the fish may be aligned to one side, or vice versa. Such misalignment can make it very difficult to latch onto the fish with the fishing tool.
The possibility for such misalignment is even more likely to occur when the fish lies in a highly deviated or horizontal hole. In such situations, the operator usually relies upon gravity to deflect the fishing tool toward the same side of the casing as the uphole end of the fish. However, where an inflation element or whipstock is lodged in a highly deviated bore hole or casing, the uphole end of the fish may be positioned in the center of the hole, or even near the upper side of the deviated hole. Where gravity deflects the latch mechanism of the fishing tool toward the lower side of the deviated hole, latching onto this type of fish may be impractical at best. Since the present invention addresses the alignment of fish and fishing tools in deviated holes as well as vertical holes, the terms uphole and downhole will generally be used herein, it being understood that these terms mean the same as the terms upper and lower, respectively, in a vertical hole.
The currently known fishing tool may have bow centralizers installed to position the latch mechanism, or bent subs may be used to orient the latch mechanism properly via a trial and error type operation. These methods can be less than satisfactory, and they can consume valuable time.